Bicolor surface reliefs in azobenzene side-chain polymers

Holographic studies in azobenzene side-chain polymers reveal light-induced periodic surface reliefs at temperatures far below the glass transition tem perature. We performed experiments with two-color holography on an azobenze ne polymer. An intensive and linear polarized homogeneous blue pump beam il luminated the sample, and two red beams-outside the trans-azobenzene absorp tion-were used to inscribe the grating. A surface relief was obtained only with the pump beam on and only if its polarization was perpendicular to the writing beams. The findings are discussed in the frame of a recent mean-fi eld model. (C) 2001 Optical Society of America.